Plate supporting and clamping apparatus



March 15, 1960 G. N. KRUEGER 2,928,161

PLATE SUPPORTING AND CLAMPING APPARATUS 5 Sheets-Sheet J.

FiledFeb. 19, 1957 INvENToR GLENN N. KRUEGEE fig March 15, 1960 G. N.KRUEGER PLATE SUPPORTING AND CLAMPING APPARATUS Filed Feb. 19, 1957 3Sheets-Sheet 2 N INVENTOR GLENN N. KRUEGER If wwflglw, flaw/M ATTY.

G. N. KRUEGER PLATE SUPPORTING AND CLAMPING APPARATUS 3 Sheets-Sheet 3 Wa M o m m WM x. mm m n plcu V 5 J March 15, 1960 Filed Feb. 19. 1957ATTYS,

United stms atfi 073C? PLATE SUPPORTING AND CLAMPING APPARATUS GlennKrueger, North Riverside, Illi, assignor Miehle-Goss-Dexter,Incorporated, Wilmington; Del., a corporation of'Delaware ApplicationFebruary 19 1 957,S erial No, 641,036

10 claims. or. 29 -2H the plates and apply circumferential tension todraw themlsecui'ely against the press cylinders. For receiving the hooksor fingers of the plate holdingmechaiiisms, recesses, calledtensionlockup pockets; aremilled inthe underside of the curved printingplates adjacent their straight edges. It'is customary to'rnillsuchrecessesf or pockets after the printing plates have otherwise" beencompletely prepared for printing, including the ste'p of shaving theundersides of such. plates" to-a finisheddie m'ension conforming to'the" outer" surface of 5 a printing cylinder in order to-obtain'accuracy in 'locatin'g"the terisi on lockup pockets. I Stereotypeprinting plates which are to print ordinary copy in black ink arepositioned on the'different'press cylinders for sidelay andcircumferential register. Accordingly, in finishing: such plates, thetension lock-up pockets milled in the unclersides of eachplate-should'jbe located in substantially 'thesameposition withrespectdo the copy on the outside of the plates; Stereotype printingplates which are to printan image in' colo'r, however; must beregistered exactly onthe different p'resscylin'd'ers so that each colorimage printed is' in perfect re'gister with previously printed images;The" tensionlockup pockets in each of the several plates required toprinter color image should'be located' in the same position with respectto the image on the plate, in order to permit final adjustment for exactregister by means of 'th' plat e adjusting mechanism provided 'inconjunction with -the plate lockup mechanism onthe press'cylind'rfMilling machines particularly adapted to prepare stereotype printingplates by cuttingp'o'ckets on the underside of the platehave'becoinewell known? An exainple of an improved plate finishingmachine of this type may be seen by reference toapplicantsrelafe'd'app'lication, Serial No. 641,176, filed February 19; 1957;

clamping apparatus so that 'the'"*plate"-can be accurately vloeatedibefore being cu-t.

. 2,928,161 fiiQ-Md'? 15%. 1.

Accordingly,it is a general object of the invention to provide clampingapparatus for a plate finishing chine for holding a stereotype printingplate in 126s formilling which is effective to prevent moyem'e" theplate during operation of the milling unit yet does not damage ordistortthe plate or its printingiimiage'; more detail, it is an object isprovide clamping app ms for a saddle type plate finishing machine for? ap in'g clamping pressure to a plate on the saddle at steady rate anduniformly byrnea'ns of a curved res" ant band so that the plate isnot-m'a r'red'nor is it" SjtraihEii out ofaccurate alinernent. p v Itis, another object to proyide a, plate cramping am} su porting apparatusthat permits accurate r' 'e'gis any portion of a plate surface. A*furthei obj provide a' clamping apparatus which isconve'm"" mounted overthe saddle of the machine 'for' lengthwise sliding movement-relative tothe same, so that thclanip ing apparatus may be easily shifted away fromthe regi'dii of the saddle in which the plateis to be machine" 6 permitthe plate to be accurately located prior to" ehining'. A related object'is tomoun't' the clamping paratus on a yielding support so as to takeupany dc"- flection during clamping.

In'more detail, an object isto provideaclampha a rigid arcuate bodymoiinted to' lie adjacent to butspaced above the saddle slightlyriiore'tha'n the" thickness are printing plate, and a resilient bandsupportedby body and movable by' an actuator controlled by pressurefluid to expand'into contactwith' a plate'to" fimrly- Hold thes'ame onthe saddle. Another object is to provide ail, important safety featureby employing means limiting the" movement of the" clamping-band,"thuspi'ov'idi a safeguard against' the" actuator for the clampburst' as.whentheclampis ac'tuated'whe're no pla'te 'is under the" clamp, or" dueto the application'of excessive "fluid press;

substantially in the plane of lines -.'l-:-.-7'of Fig. 5.

sures. his a further object to provide aclampin'g apparatus of thistype' that is convenient and simple" tdo 'erate, "in: expensive" tomanufacture; andconstructed' forlong fe under rigorous use. It isarelated' object to' rovide suich an'apparatus that is self adjustin'gand eas'yto maint in: Other objects and advantages of theinvention willbe com'e" apparent from the attached" description and upon referencetothe drawings,iin which: n V 7 Figure 1 is a perspective 'view oi? a'plate finishing;Ina chine equipped with plate clamp apparatus"constructed in'accord-with' this invention; Figs. 2 and 3 areat'op' planview"and' a"side elevation view; respectively, of the machine ofFigure1;

Fi'g.-4- isa'sectional view taken' substantiall'y" iii th plane of lines4- 4 of'Fig: 2; r Fig.5 is an enlarged sectional view ofone plateclamp'taken substantially in the-plane 'of"lines'-'5 5'of"Fi 4" Fig. '6 is anenlarged fragmentary sectional vie one plate clamp taken substantially"in the plane oflines. 6,6'"of Fig. 5 and showingapart of the lowefendoftheclamn; and l L Fig. 7 is a 'section'aFview .of oii'e' plate clamptaken While the invention is susceptible of {various mbd'ific tions andalternative constructions, a preferred embodfi ment-has' been showninthe" drawings" and 'will be desc'ribed in'detail. It should beunderstdod, however; that there is" no. intention to'lirnitthe"invention route specific form disclosed, but on the contrary, the intionsyand equivalentifallin g' within thespir'it and of: the inventionas expressed in the appended claims? G enral machine or gdhi 'z'aiioriUpondmore s ecific:rerernee w tu "hammerswill be understood that theclamping apparatus of this invention is shown as embodied in anillustrative stereotype printing plate finishing machine which may bemade as part of a complete production type unit for making stereotypeplates. This machine is used for milling tension lockup pockets in theinner surfaces of the plates. A detailed description of such aproduction unit including a detailed description of the operatingcomponents of the particular finishing machine 20 shown in Figure 1, iscontained in the aforementioned co-pending application, Serial No.641,176, filed February 19, 1957. Insofar as is helpful to obtain acomplete understanding of the present invention and by way of settingthe general environment for this invention, the machine 20 of Figure 1will be described in brief.

It is customary to make this milling machine 20 as an entirely separateunit, and in independent operation as it might be shown in this figure,the machine may be supplied with plates requiring tension lockup pocketsfrom any plate production method. Accordingly, turning to Figs. 1-4, themachine comprises a waist-high frame having a massive curved saddle 26ribbed underneath for strengthening purposes, and which is provided forsupporting a semi-cylindrical stereotype plate, duringthe operation ofmilling pockets in the underside of the plate. The curved saddle 26 iselongated and extends lengthwise of the machine, and the printing plateto be milled'may be slid from the right-hand end 24 of the machine 20,as viewed in Figure 1, along the saddle to a central region whereelongated openings 27, 28 are provided through which a pair of cutters30, 31

of a milling unit 32 reach to engage the inner surfaces of the plates tomill the pockets. Inthis central region of the saddle 26, clampingapparatus 35 constructed in accord with the present invention may beutilized for clamping the plate on the saddle during a pocket millingoperation, and it is with this clamping apparatus that 'we areprincipally concerned. This clamping apparatus provides, in the presentinstance, a pair of rigid 'arcuate clamp bodies 36, 37 each having aband 38 which engages the outside of a plate positioned on the saddle ofthe machine beneath the clamps to hold it firmly on the saddle. In theexemplary form of the invention shown, air under pressure is supplied toan actuator associated with each of the clamp bodies to move the bandsand operate the clamps.

Continuing the general description of the machine 20, the frame of themachine beneath the saddle 26 is provided with horizontally extendingways 39 providing inwardly sloping way surfaces 40 forming a track forthe milling unit 32. This milling unit 32, in the present instance,embodies a sliding'carriage 42 carrying a pair of milling heads 43, 44under the saddle. These milling heads are adapted to be rocked inunison, into and out of engagement with the inner surface of a printingplate clamped on the saddle. For this purpose the machine provides camor tracer control for the milling heads which is effective as anincident'to travel of the carriage along the ways for causing thecutters to move successrvely into and out of engagement with the innersurface of the plate as the milling unit moves along under the plate.Thus the milling unit 32 is employed to cut a pattern of spaced tensionlockup pockets or recesses along both straight edges of the plateclamped on the saddle.

The carriage 42 is moved along the ways by means such; as an electricmotor (not shown) carried by the carnage and controlled by push buttonsor other controls located together in a control box 45 at the right-handend of the machine as viewed in Figure 1. Means are also provided foradjusting the saddle 26 of the machine to vary the position of a plateresting on the saddle with relation to the milling unit supported by thecarriage and under the saddle. Controls for making these saddleadjustments may be in the form of hand whee s 46., 7

4 controlling linkages and gearing at opposite ends of the machine forappropriately moving the machine saddle.

For the purpose of providing power for operating the milling unit,various arrangements may be provided, although in the machine of theaforementioned co-pending application the same motor (not shown) mountedon the carriage for driving the milling unit axially beneath the saddlealso supplies power to the milling heads to rotate the cutters. Thus inthis machine 20 the milling unit 32 comprises a unitary assembly ofsubstantial weight resting on the machine frame ways, and provides astable platform for the milling cutters enabling their operation withgreater precision and at higher cutting speeds. Suitable means (notshown) may be provided for supplying electric power to the motor on thetraveling carriage, controlled by means of the control box found on theright-hand side of the machine as viewed in Figure 1.

As indicated most clearly in Figures 13, the machine 20 may be providedwith means for locating stereotype plates on the saddle of the machine,in the present instance comprising stops controlled by handles 56 foundat one end of the saddle. These plate steps 55 are arranged on bothsides of the saddle towards the righthand end of the machine as viewedin Figs. 1-3, the end of the machine on which the plates are firstreceived, and serve as locating stops against which the plate abutsprior to clamping so as to properly position the plate for receiving thetension lockup pockets. So as to enable a printing plate to slide pastthese stops 55 without manual manipulation, the stops 55 are springbiased to the erect position in which they are shown in these figures.Thus the stops are depressed by the weight of a plate as it slides overthem to the central machining region of the saddle. Stops 57 may also beprovided towards the terminal end of the saddle 26, for skewing a plateon the saddle before clamping for color plate registering purposes. Suchskewing stops 57 are normally drawn away from the plate engagingposition when ordinary black printing plates are machined by means ofoperating handles 57. It will be understood other mechanism may beemployed for locating the plate or adjusting it with relation to thesaddle 26 than that shown herein, this form being depicted forillustrative purposes only. In addition to providing for milling pocketsin the inner surface of the plate, this machine 20 also ordinarilyprovides means (not shown) for trimming opposite corners of the platefor sidelay registry purposes. The supports 58, 59 for the trimmingcutter shafts 60, 61 are mounted on the frame of the machine, as shownin Figure 1.

Plate clamping apparatus For holding a plate on the saddle of themachine 28 during the milling operation, the present invention providespressure fluid operated clamping apparatus 3 5, shown in Figure 1positioned over a plate P located in the central region of the saddle26. As described hereinbefore, with the plate P held rigidly on thesaddle 26, the milling unit 32 under the saddle is effective to milltension lockup pockets adjacent both straight edges of the plate.

The cutters of the milling unit reach through the elongated openings 27,28 (Fig. 4) in the saddle 26 to engage the inner surfaces of the plate Pmounted on the saddle for milling purposes. The contour of the saddle 26is cylindrical to conform to the finished inner surface of a stereotypeprinting plate, and the saddle provides a reference surface on which theplate may be accurately located so as to enable the tension lockuppockets to be precisely located in the plate. For facilitating suchadjustment, provision may be made such as plate locating stops 55 andskewing stops 57, as described earlier, carried on the saddle andadjusted by means of control handles 56, 57 respectively.

,In carrying out the invention, the clamping apparatus ,74, 75 of theclamping rings.

.also the return'springs'of the assembly.

by cooperating with the flanges 7,4, 75 of theclamping embodies a pairof arcuate' clamps embodying;- clamp bodies 36, 3 1 aremounted over thesaddle such as to: permit adjustment lengthwise thereof in order to Bepositioncd over a plate Iocated on the saddle as shown in Figure I.Ordinarily in clamping a plate these clamp bodieswould be spaced apartsomewhat less than the width of the; plate. For supporting the clampbodies 36, 37 on the frame 25 of the machine, parallel rods 65, whichlie lengthwise of and adjacent to the saddle are utilized; The ends ofthe clamp bodies 36, 37 are sl'idably supported on rods 65, 66 by meansof bushings 69, 70 which also act as spacers to hold the clamp bodiesapart; The arcuate clamp bodies, as shown in Figures 1 and 4, are curvedto closely overlie the saddle "and in the present instance are spacedslightly more, perhaps" Ma", than the thickness of aprinting plate fromthe surface of the saddle, as shown in Fig. 61

In accordance with the present invention, for clamping purposes aresilient band 38 is mounted under each clamp body 36, 37 and anactuator is associated therewith, operated by pressure fluid, for movingthe band 38 into engagement with a plate P under the clamping apparatus.for urging the plate onto the saddle with uniform pressure and thus forholding it in position without distortion. Since the clamps of theapparatus are alike,

the description which follows applies to both clamps.

For supportinng the resilient band'38, the arcuate rigid clamp back orbody 36 is channeled and receives curved mountingrings 72, 73 L-shapedin section on the under side along the opposite edges. The flanges 74,75 of the L-shapedv mounting rings 72, 73 are so dimensioned as to.leave a slot 76' running lengthwise of the clamp body on the underconcave side 77, the width of the slot: being substantially less thanthe over-all width of the clamp body, as shown in Fig. 5. The resilientband 38" fits in the slot 76v with some play to permit in. and

out movement.

In the present instance the actuator 71 comprises a flexible diaphragm80, made of cordedrubber fabric, for example, which is held in positionover the channeled 6 If no: plate is under the clamp, the band 38 movesoutwardly' until the plate 82 is stopped by the flanges 74, 75 of themounting rings and the waved springs 86, 87 compressed between thesemembers.

In the present instance the backing plate 82 for the resilient band 38terminates a short distance from the end of the pressure fluid chamberformed within the concave under surface 81 of the clamp body 36 by means.extend'slaterally on both sides of the band, as shown in Big. 5., and,presents portions lying behind thev flanges A thin strip of steel. 84approximately .010" in thickness is placed between strip Bland thediaphragm to protect the diaphragm from possible damage from burrs orscufling of rivets during operation. This strip is the same width andlength. as strip82.

For. supporting the band 38 in place a strip Between the lateral flanges74, 75 of the clamping I supported on the clamping band 38, strips ofspring steel 86, 87' waved. or serpentine in form are inserted. Thesestrips 86,-.87 functionas springs for returning the band 38 to:withi nthe clamp body 36 upon release of fluid pressure. The backing. plate 82for. the band 38, in the present instance, performs a multiple function.It presents arigid member which holds the band in position. The plate-82also coacts with the diaphragm and In addition,

rings, it operates to limit the outward movement of the-band; Upon theapplication of pressure fluid to the chamber,, diaphragm 80" stretches,and moves-the band "38'outwardly through the slot 76't0 extend from theclamp body 36 for engagement with the plate P located under the clampingapparatus 35 on the saddle of the machine.

clamp body, which is defined at each end of the body by diaphragm endclamps 88. One of these end clamps 88 appears in section in Fig; 6. Overextended periods of operation of the clamp actuator 71, it has beenfound that the diaphragm has been damaged inthe regions adjacent theends of the steel strip 84 due to rubbing or abrasion between the stripand the diaphragm; To prevent such damage in the present instance,shortend strips 89 are placed between the diaphragm and the ends of thebacking-plate at each: end of: the clamp; Only one of these end strips89appe'ars in the drawings, also in Fig. 6. It will be apparent from thedrawing that the end strips extend under end clamps; 88 and are held inplace by them.

A further feature contributing to the trouble-free operation of' theclamping: apparatus illustrated, is provided by the mounting arrangementfor the spaced clampsl- In the present instance, mounting rods 65, 66are employed located on each side of the saddle and so positioned as toenable manual sliding movement of the clamps to a position over thecentral region of the saddle and over pressure fluid actuator 72 foreachclamp maybe operated toexpand the resilient band 38 into engagementwith the outside of the printing plate P. In the present instance, the(Fig. 7) clamping band 38 is made of a somewhat resilient yet toughsubstance such as hard gum rubber which will not abrade or mar theoutside of the stereotype plate. Since the outside of the plate alreadycarries the printingirnage it is essentialthat the same not be damagedby the clamping. apparatus.

To resist transverse binding while still allowing flexure lengthwise toconform to the concavity of the' clamp body the backing stop or plate 82must be made of a relatively stiff and strong material such as springsteel. With such 'a material forming the backing for the band, and withthe pressure fluid actuator shown as exemplary in the drawings, theclamping bandupon: actuation engages a plate in such a manner as tominimize the chances of marring the outside surface of the plate anddistortingthe plate. In part this is clue to the feature that theclamping band apparently does not engage the outside of the platethroughout its length at the same instant. Rather, from observation, ithas been concluded that initially the plate is engagedby the bandintermediate'the ends thereof, that is to say, over the crown of thesaddle, and clamping e'ngagement proceeds in both directions towards therespective ends of the clamp. It is evident'that'the time intervalduring which this occurs is of very short duration. The clamping band inall regions thus presses squarely against the outside of'the'plateandthere is an absence of rubbing even during initial pressure application.

Moreover, there is an entire absence of. circumferential stressesapplied to the plate and, as a result, thereisino tendency to shift the"plate on the" saddle duringclamp actuation. p

Iclaim asmyinvention:

V 1". In a machine forfinish'in'g curved'stereotype printing plates andhaving a frame supporting a cutter which engages the inner surface ofthe plates, a plate-supporting and clamping apparatus comprising, incombination, a saddle on said frame having an opening permitting-saidcutter to operate therethrough, said saddle being curved to support aplate,:an arcuate clamp positionable over said saddle, means forsupporting said clamp on said frame including parallel rods lyinglengthwise of and adjacent to said saddle, said rods being supported bythe machine frame, said clamp having a clamp body supported at its endsby said rods and being curved to closely overlie said saddle, andpressure fluid means carried by said clamp body, said pressure fluidmeans including a clamping band supported on the underside of said bodyand operable when the clamp is positioned over a plate on said saddle tomove into engagement with the plate for urging the plate onto the saddlewith uniform pressure and holding it in position without distortion.

' 2. In a machine for milling tension lockup pockets in curvedstereotype printing plates and having a frame supportinga cutter whichengages the inner surface of the plates, a'plate-supporting and clampingapparatus comprising, in combination, a saddle on said frame having anopening permitting said cutter to operate therethrough,

said saddle being curved to support a plate, an arcuate clamppositionable over said saddle, said clamp having a clamp body curved toclosely overlie said saddle, means for supporting said clamp body onsaid frame, said support means allowing for adjusting the position ofsaid clamp body lengthwise of the frame, and means carried by said clampoperable when the clamp body is positioned over a plate on said saddlefor engaging the said plate, said last-named means including a resilientband supported on the underside or said clamp body for urging the plate.onto the saddle with uniform pressure and thus holding it in positionwithout distortion.

3. A pressure fluid operated clamp comprising, in combination, anarcuate clamp body, means on the concave underside of said body forminga lengthwise slot, a resilient band in said slot and movable outwardlyto extend from said clamp body for clamping purposes, said clamp bodyforming a chamber for pressure fluid behind said band, a pressureresponsive member mounted in said chamber for moving said band, and aninflexible plate attached to .said band to extend laterally thereof,said plate being sub- ,stantially wider than said slot to limit theoutward movement of said band upon the application of pressure fluid tosaid chamber.

4. A pressure fluid operated clamp comprising, in combination, anarcuate clamp body having means forming a slot running lengthwise of thebody on the under concave side thereof, a resilient band in said slotand movable outwardly to extend from said clamp body for clamping,purposes, said clamp body forming a chamber for pressure fluid behindsaid band, a pressure responsive'mem- 'ber mounted in said chamber formoving said band, an

inflexible plate attached to said band to extend laterally thereof, saidplate being substantially wider than said slot to limit the outwardmovement of said band upon the application of pressure fluid to saidchamber, and an elongated waved spring acting against the lateralportion of said plate for returning said band upon the release ofpressure.

5. A pressure fluid operated clamp comprising, in commeans carried bysaid band and cooperating with a stop on the clamp body for preventingsaid diaphragm from bulging out said wall opening under excessivepressure conditions.

6. A pressure fluid operated clamp comprising, in combination, a clampbody including a side wall having an opening therein, a chamber forpressure fluid formedin said body behind said wall, a diaphragmcompleting said chamber, a resilient clamping member supported in thewall opening and movable by said diaphragm to extend from said body forclamping purposes, andstop means carried by said clamping member forpreventing said diaphragm from bulging out said wall opening underexcessive pressure conditions.

7. A pressure fluid operated clamp comprising, in combination, anarcuate clamp body having a chamber extending lengthwise thereof forpressure fluid leaving a slot to the concave side of said body openingto the outside of said body, a diaphragm positioned acrosssaid slot, aresilient band supported within the clamp body in the slot and movableby said diaphragm upon the application of pressure to extend from saidbody for clamping purposes, and spring means carried by said bodyforreturning the band within the clamp body upon release of pressure. v

8. A pressure fluid clamp comprising, in combination, a clamp bodyforming a chamber for pressure fluid, a diaphragm closing said chamber,a resilient band supported by said body and movable by said diaphragmfor clamping purposes, and means carried by said resilient bandcooperating with means carried by said body for limiting the movement ofsaid band thus safeguarding the diaphragm from bursting under excessivepressure conditions. r

9. In a machine for finishing curved stereotype printing plates andhaving a frame supporting a cutter which engages the inner surface of aplate to be finished, plate supporting and clamping apparatuscomprising, in combination, a curved saddle carried by said frame havingan opening for said cutter to operate through, anarcuate clamp carriedby said frame over said saddle, said clamp having a rigid clamp bodycurved to closely overlie said saddle and spaced uniformly therefrom ata distance slightly more than the thickness of a plate so as to permit aplate to be positioned on said saddle under said clamp body, andpressure fluid means supported by said clamp body including a flexibleclamping band mounted on the underside of said body and engageable witha plate on the saddle, said last-named means being operable to move saidclamping band into engagement with a plate for urging the latter ontothe saddle with uniform pressure and thus holding it in position withoutdistortion.

10. In a machine for finishing curved stereotype printplates and havinga frame supporting a cutter which engages the inner surface of a plateto be finished, plate supporting and clamping apparatus comprising, incombination, a curved saddle carried by said frame having an opening forsaid cutter to operate through, an arcuate clamp carried by said frameover said saddle, said clamp having a rigid clamp body supported at itsends on said frame and curved to closely overlie said saddle and spaceduniformly therefrom at a distance slightly more than the thickness of aplate so as to permit a plate to be positioned on said saddle under saidclamp body, and pressure fluid means supported by said clamp bodyincluding a flexible clamping band mounted on the underside of said bodyand engageable with a plate on the saddle, said last-named means beingoperable to move said clamping band into engagement with a plate forurging the latter onto the saddle with uniform pressure and thus holdingit in position without distortion.

References Cited in the file of this patent UNITED STATES PATENTS2,366,666 Chapman Jan. 2, 1945 2,537,604 Ricards et al. Jan. 9,19512,640,565 Hoppenstand Jan. 2, 1953 2,673,573 Fawick Mar. '30, 19542,680,405

